1. Field of the Invention
This invention relates to industrial burners and, more particularly, recuperative and regenerative burners which utilize the Coanda Effect.
2. Description of the Prior Art
Conventional industrial burners are typically configured in a symmetrical fashion. In this symmetrical configuration, a fuel conduit is generally disposed axially along a centerline of the burner and combustion air is generally introduced immediately about a periphery of the fuel conduit or, with appropriate air ducting, symmetrically about the fuel conduit and radially spaced therefrom. A prior art example of a symmetrical industrial burner is disclosed by U.S. Pat. No. 3,876,362 to Hirose. The symmetrical or xe2x80x9caxialxe2x80x9d burner disclosed by the Hirose patent attempts to induce a deflected stream of gas from the burner by providing an air inlet in the burner tile structure. The positive axial mass flux of the air and fuel jets cause a recirculation of POC from the furnace chamber into the burner tile. This induction of POC into the burner tile and subsequent entrainment into the fuel and air streams causes lower flame temperatures and lower NOx production rates.
An object of the present invention is to provide a burner that obtains NOx levels lower than those disclosed in the Hirose patent.
It is a further object of the present invention to address the problem of saving space in burner constructions, particularly as applied to regenerative and recuperative burners.
It is still a further object of the present invention to maximize air and fuel entrainment with products of combustion through means of a burner configuration that minimizes NOx formation.
The above objects are accomplished with a burner for non-symmetrical combustion made in accordance with the present invention. The burner generally includes a burner housing enclosing a burner plenum. A fuel conduit extends longitudinally within the housing and is positioned coaxial with a line spaced from a central axis of the burner. The fuel conduit defines a fuel exit opening. An air conduit extends into the housing and defines an air opening on an opposite side of the burner central axis from the fuel exit opening. The air opening is preferably positioned a greater distance away from the burner central axis than the fuel exit opening. The air conduit may have a cross-sectional shape in the form of a circle segment defined by a chord.
A baffle is preferably positioned at least partially around the fuel conduit and defines the air conduit. The baffle may further define a primary stabilization cavity immediately adjacent the fuel exit opening. The cavity may be in fluid communication with the fuel conduit through the fuel exit opening. The cavity may be cylindrical-shaped and coaxial with the fuel conduit.
A burner port block may be connected to the baffle downstream of the fuel exit opening. The burner port block preferably has a sidewall diverging from the burner central axis. The sidewall preferably diverges at a flare angle of between approximately 2xc2x0 and approximately 30xc2x0. The baffle may separate the burner port block from the burner plenum. A combustion gas conduit may extend through the burner plenum and connect to the cavity. The fuel conduit may be positioned within the combustion gas conduit. Swirl vanes may be positioned within the combustion gas conduit and be peripherally spaced around the fuel conduit. An auxiliary fuel conduit may extend through the burner plenum and connect to the burner port block. The auxiliary fuel conduit may define an auxiliary fuel exit opening radially spaced from the fuel exit opening and coterminous with the burner port block. The fuel exit opening may be positioned on the opposite side of the burner central axis from the air opening.
The burner plenum may at least be partially filled with heat transfer media. Alternatively, the burner plenum may be connected to a diverter valve configured to selectively admit combustion gas into the combustion gas conduit. The present invention also includes a method of non-symmetric combustion.
Further details and advantages of the present invention will become apparent from the following detailed description in conjunction with the accompanying drawings, wherein like reference numerals designate like parts throughout.